With probably a million miles traveled in a variety of vans, playing practically every club in the country, graduating to festivals, and now, serving as top-tier arena headliners, Twenty One Pilots have clearly made the most of the grind. But more than just putting in the hours, much of the reason front man/multi-instrumentalist Tyler Joseph and drummer Josh Dun sold out the United Center several months in advance has to do with a mash-up that flirts with alt-rock, hip-hop, indie pop and EDM without ever fully committing to one, and in the process, coming across as absolutely unclassifiable yet creative ear candy.

The set reached its emotional epicenter with reflections on a stolen “Car Radio” featuring everyone screaming along to heavy lines like “sometimes quiet is violent…I’m forced to deal with what I feel…there is no distraction to mask what is real” as the track’s piano pop beginnings exploded into electronic grenades, stacks of smoke and an overriding impression that Twenty One Pilots’ take off is more than temporary.

Though much of the crowd skewed towards the younger side (unless they were accompanied by their parents), both guys are in their upper 20s and talking about complex issues including anxiety, depression, isolation, and ultimately, reaching for hope. As those messages have taken root across an exponentially swelling fan base, Twenty One Pilots have continued to sculpt the extensive “Emotional Roadshow” into a purpose-filled party that in Chicago found the fellas switching instruments, hats, masks and clothes in between racing around the standard stage, back flipping off the piano, climbing up soundboard scaffolding and popping up in the balcony courtesy of an impressive optical illusion.

All the while, the duo delivered cuts from the blockbuster “Blurryface,” its predecessor “Vessel” and a few others, starting with the fitting “Heavydirtysoul,” the dusty groove “Heathens,” the electro/hip-hop collision “Lane Boy,” the soulful pop of “Stressed Out” and The Killers-tipped “Tear In My Heart.” Even with all that eclectic energy, the strong show could’ve been spectacular, if only Twenty One Pilots trimmed some fat, such as a four song segment of unremarkable ‘90s covers with otherwise connective openers Jon Bellion and Judah And The Lion, Josh drum dueling with a videotaped version of himself or Tyler challenging a fan to a round of “Mario Kart 64.”

Regardless, everyone seemed to eat it all up and were made to feel like instant members of the “Skeleton Clique,” which was most apparent during “Ride” and also at the end of “Trees” when the guys and their respective mini-drum kits were supported crowd surfing-style above the audience’s heads. Somewhere in between those two monster tunes, the set reached its emotional epicenter with reflections on a stolen “Car Radio” featuring everyone screaming along to heavy lines like “sometimes quiet is violent…I’m forced to deal with what I feel…there is no distraction to mask what is real” as the track’s piano pop beginnings exploded into electronic grenades, stacks of smoke and an overriding impression that Twenty One Pilots’ take off is more than temporary.